tbbr: Add build flag HASH_ALG to let the user to select the SHA

The flag support the following values:
    - sha256 (default)
    - sha384
    - sha512

Change-Id: I7a49d858c361e993949cf6ada0a86575c3291066
Signed-off-by: Qixiang Xu <qixiang.xu@arm.com>

docs/user-guide.rst

@@ -425,11 +425,15 @@ Common build options
 
 -  ``KEY_ALG``: This build flag enables the user to select the algorithm to be
    used for generating the PKCS keys and subsequent signing of the certificate.
-   It accepts 3 values viz ``rsa``, ``rsa_1_5``, ``ecdsa``. The ``rsa_1_5`` is
+   It accepts 3 values viz. ``rsa``, ``rsa_1_5``, ``ecdsa``. The ``rsa_1_5`` is
    the legacy PKCS#1 RSA 1.5 algorithm which is not TBBR compliant and is
    retained only for compatibility. The default value of this flag is ``rsa``
    which is the TBBR compliant PKCS#1 RSA 2.1 scheme.
 
+-  ``HASH_ALG``: This build flag enables the user to select the secure hash
+   algorithm. It accepts 3 values viz. ``sha256``, ``sha384``, ``sha512``.
+   The default value of this flag is ``sha256``.
+
 -  ``LDFLAGS``: Extra user options appended to the linkers' command line in
    addition to the one set by the build system.
 

drivers/auth/mbedtls/mbedtls_crypto.c

 /*
- * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -7,6 +7,7 @@
 #include <crypto_mod.h>
 #include <debug.h>
 #include <mbedtls_common.h>
+#include <mbedtls_config.h>
 #include <stddef.h>
 #include <string.h>
 

drivers/auth/mbedtls/mbedtls_crypto.mk

@@ -37,9 +37,30 @@ MBEDTLS_CRYPTO_SOURCES		:=	drivers/auth/mbedtls/mbedtls_crypto.c	\
 					pk_wrap.c 				\
 					pkparse.c 				\
 					pkwrite.c 				\
-					sha256.c				\
 					)
 
+ifeq (${HASH_ALG}, sha384)
+    MBEDTLS_CRYPTO_SOURCES  += \
+					$(addprefix ${MBEDTLS_DIR}/library/,	\
+						sha256.c            \
+						sha512.c            \
+					)
+    TF_MBEDTLS_HASH_ALG_ID	:=	TF_MBEDTLS_SHA384
+else ifeq (${HASH_ALG}, sha512)
+    MBEDTLS_CRYPTO_SOURCES  += \
+					$(addprefix ${MBEDTLS_DIR}/library/,	\
+						sha256.c            \
+						sha512.c            \
+					)
+    TF_MBEDTLS_HASH_ALG_ID	:=	TF_MBEDTLS_SHA512
+else
+    MBEDTLS_CRYPTO_SOURCES  += \
+					$(addprefix ${MBEDTLS_DIR}/library/,	\
+						sha256.c            \
+					)
+    TF_MBEDTLS_HASH_ALG_ID	:=	TF_MBEDTLS_SHA256
+endif
+
 # Key algorithm specific files
 MBEDTLS_ECDSA_CRYPTO_SOURCES	+=	$(addprefix ${MBEDTLS_DIR}/library/,	\
 					ecdsa.c					\
@@ -67,6 +88,7 @@ endif
 
 # Needs to be set to drive mbed TLS configuration correctly
 $(eval $(call add_define,TF_MBEDTLS_KEY_ALG_ID))
+$(eval $(call add_define,TF_MBEDTLS_HASH_ALG_ID))
 
 BL1_SOURCES			+=	${MBEDTLS_CRYPTO_SOURCES}
 BL2_SOURCES			+=	${MBEDTLS_CRYPTO_SOURCES}

drivers/auth/tbbr/tbbr_cot.c

@@ -19,7 +19,7 @@
  * Maximum key and hash sizes (in DER format)
  */
 #define PK_DER_LEN			294
-#define HASH_DER_LEN			51
+#define HASH_DER_LEN			83
 
 /*
  * The platform must allocate buffers to store the authentication parameters

include/drivers/auth/mbedtls/mbedtls_config.h

@@ -13,6 +13,13 @@
 #define TF_MBEDTLS_ECDSA		2
 #define TF_MBEDTLS_RSA_AND_ECDSA	3
 
+/*
+ * Hash algorithms currently supported on mbed TLS libraries
+ */
+#define TF_MBEDTLS_SHA256		1
+#define TF_MBEDTLS_SHA384		2
+#define TF_MBEDTLS_SHA512		3
+
 /*
  * Configuration file to build mbed TLS with the required features for
  * Trusted Boot
@@ -66,6 +73,9 @@
 #endif
 
 #define MBEDTLS_SHA256_C
+#if (TF_MBEDTLS_HASH_ALG_ID != TF_MBEDTLS_SHA256)
+#define MBEDTLS_SHA512_C
+#endif
 
 #define MBEDTLS_VERSION_C
 

make_helpers/tbbr/tbbr_tools.mk

@@ -54,6 +54,7 @@ $(eval $(call FWU_CERT_ADD_CMD_OPT,${FWU_CERT},--fwu-cert))
 # packed in the FIP). Developers can use their own keys by specifying the proper
 # build option in the command line when building the Trusted Firmware
 $(if ${KEY_ALG},$(eval $(call CERT_ADD_CMD_OPT,${KEY_ALG},--key-alg)))
+$(if ${HASH_ALG},$(eval $(call CERT_ADD_CMD_OPT,${HASH_ALG},--hash-alg)))
 $(if ${ROT_KEY},$(eval $(call CERT_ADD_CMD_OPT,${ROT_KEY},--rot-key)))
 $(if ${ROT_KEY},$(eval $(call FWU_CERT_ADD_CMD_OPT,${ROT_KEY},--rot-key)))
 $(if ${TRUSTED_WORLD_KEY},$(eval $(call CERT_ADD_CMD_OPT,${TRUSTED_WORLD_KEY},--trusted-world-key)))